Women who usually are restrained eaters tend to gain more weight than other women when they’re pregnant, say researchers. Excess weight gain may be linked to child obesity, so a team from the University of North Carolina at Chapel Hill investigated weight gain among women taking part in the university’s ongoing Pregnancy, Infection, and Nutrition Study.

They gave questionnaires to 1,223 participants to determine their eating habits. Based on the questionnaire results, the women were classified on the Revised Restraint Scale. Their weight was monitored during the course of their pregnancy.

The U.S. Institute of Medicine suggests women should gain 28 to 40 pounds, 25 to 35 pounds, 15 to 25 pounds and at least 15 pounds for underweight, normal weight, overweight and obese women, respectively.

Study results showed that women who were restrained eaters prior to pregnancy tended to gain weight above the Institute of Medicine recommendations. But this only applied to restrained eaters who were normal, overweight or obese before getting pregnant. Restrained eaters who were underweight at conception tended to gain weight below the recommendations during their pregnancy. They also gained less weight during pregnancy than unrestrained underweight women.

Results are published in the October 2008 issue of the Journal of the American Dietetic Association.

Dr. Anna Maria Siega-Riz believes that the Revised Restraint Scale tool is useful for identifying women who would benefit from nutritional counseling prior to or during pregnancy in order to achieve targeted weight-gain goals. The study findings “could potentially be used by dietitians and health care providers at a preconception care visit or during family planning to identify women at risk for unhealthy eating behaviors,” she said.

She added that the women in the study, particularly those who are underweight, should be followed up for potential eating disorders. Women who are not underweight should receive counseling and extra support to encourage healthy eating behaviors, increased physical activity levels, and “ways to eliminate stress which may increase the consumption of foods in certain social settings or in reaction to life events.”

Excessive weight gain during pregnancy may lead to the need for a Caesarean section. It may also cause large-for-gestational age (LGA) babies, and is linked to a shorter duration of breastfeeding and higher postpartum weight retention. Earlier research also indicated that a higher body mass index among mothers puts infants at a greater risk for birth defects of the kidney.

Dr. Siega-Riz’s team has previously examined the “perceived barriers” to physical activity among pregnant women. She explains that physical activity usually declines during pregnancy. But the barriers to activity during pregnancy are not well understood.

In this study, she gathered information about attitudes toward exercise by giving a questionnaire to 1,535 pregnant women in the Pregnancy, Infection, and Nutrition Study. The findings were then investigated in more depth with focus groups.

Most (85 percent) of the women reported one or more barriers to physical activity. Almost two-thirds of the barriers were health-related. Since pregnancy may trigger the development of obesity, Dr. Siega-Riz said, physicians should promote healthy physical activity for pregnant women.

Using a much larger group of women, Dr. Siega-Riz looked at the impact of eating disorders on pregnancy. She took data from 35,929 pregnant women in the Norwegian Mother and Child Cohort Study. Of these women 35 reported having anorexia nervosa, 304 bulimia nervosa, and 1,812 binge eating disorder, in the six months before pregnancy.

Mothers in all of these groups reported greater gestational weight gain than women with no eating disorder. Binge eating disorder was particularly associated with higher maternal weight gain. Although “adequate gestational weight gain” found in anorexic mothers may mitigate against adverse birth outcomes, the researchers state that “detecting eating disorders in pregnancy could identify modifiable factors that influence birth outcomes.”

Further analysis of diet revealed that women with binge-eating disorder had higher energy and fat intakes during pregnancy, and lower intakes of several vitamins, than women without an eating disorder. This was also true of women who developed binge-eating disorder during pregnancy.

“Several differences emerged in food group consumption between women with and without eating disorders, including intakes of artificial sweeteners, sweets, juice, fruit, and fats,” say the researchers. These differences “may influence pregnancy outcomes,” the experts warn.

References

Slickers, J. E. et al. Maternal Body Mass Index and Lifestyle Exposures and the Risk of Bilateral Renal Agenesis or Hypoplasia: The National Birth Defects Prevention Study. The American Journal of Epidemiology, published online October 3, 2008.

Bulik, C. M. et al. Birth outcomes in women with eating disorders in the Norwegian Mother and Child cohort study (MoBa). The International Journal of Eating Disorders, published online August 21, 2008.

Siega-Riz, A. M. et al. Nutrient and food group intakes of women with and without bulimia nervosa and binge eating disorder during pregnancy. The American Journal of Clinical Nutrition, Vol. 87, May 2008, pp. 1346-55.